Colorimetric detennination of pyrogallol and 2,6-dimethoxyphenol with diphenylpicrylhydrazyl.

A colorimetric study was made of the reactions of the free radical 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the phenols pyrogallol and 2,6-dimethoxyphenol. Both of these phenols were colorimetrically determined by use of DPPH, in the presence of various interferents. It was shown that the determination of pyrogallol and 2,6-dimethoxyphenol was more accurate when absolute ethanol was used than with 95 % ethanol. It was also shown that the best results were obtained when the ratio of phenol to interferent was no greater than 1:1.